Hydraulic speed governor for prime movers



April 6, 1954 i R. J. IFIELD HYDRAULIC SPEED GOVERNOR FOR PRIME MOVERSFiled Aug. 21, 1950 Patented Apr. 6, 1954 PATENT omcg HYiiRAUL'Ios'rliiioggy zo mwon FoR PmME Richa'r d vJoseph Ifield, Dural, newsmanwales, Australia, assignor to Joseph Lucas Limited, Birmingham, EnglandAp'plicationAligu St 21, 1950, Serial N0.180,656

Claims priority,"application Great Britain August 22, 1949 Claims. (CL'103-11) This invention relates to hydraulic governors for prime movers,such as jet propulsion engines, gas turbines and the like, the governorsbeing ofthe kind adapted to control a liquid-operated servo mechanismfor varyingthe output-of a fuel supply pump or otherwise regulating thesupply of fuelto the prim mover in responseto variatijons of speed. t tt 'The inventionhas for its object toenable the speed at which" thegovernor comes: into action to be kept substantially constant over awide range of variation of the'rate at which the fuel is supplied to theprime'rnover. V I H I The invention comprises the combination of a valvefor controlling th servo'r'nechanism, liquid-operable means for 1actuating the valve, the said meansbeing in communication withaby-passpassage extending from the'fuel supply system, a variablethrottle, adapted to control the flow of liquid through the bypa'ss'passage, a dash pot responsive tothe pressure of the liquid in thesaid passagefor actuatingthe'throttle, and means adapted'to'set upin'the said passage a counterpressure related to thespeed of the primemover.

The invention also comprises the combination withthe' means specified inthe preceding paragraph, of an isolating valve for temporarily closingthe'bypalss passage while the prime mover is being started.

The accompanying drawing illustrates diagrammatically one embodiment ofthe invention. Y j Referring to the drawing, the liquid fuel supply pump there shown is of known form and comprisesa rotor a having'thereinaplurality of bores each containing a spring-loaded plunger b,'the rotorbeing contained in a housing 0. Actuation of the pl'ungers is effectedby a swash plate d. For adjusting the obliquity of theswash plate thereis provided a liquid operated servo mechanism, which consists of apiston e connected to the swash plate by 'arod f. The piston is slidablein a cylindrical chamber 9 andis loaded at one side by a spring h. Thetwo ends of the cylinder are interconnectedby a'passage 2' containing arestricted orifice'y, and the end of the chamber gremote from thespringis in communication with the discharge passage is of the pump. The endof the chamber 9 containmg the spring h is' in communication with apassagem leading to the "seating no: avalve 'o,' which' is carried by alever 1) and loaded by'a 'springi q. Ilie-parts n o, 'p, q, are"contained-' in a 'chambr' r"which is in communication with the inletpassage 2, and "which is separatedfromfan'adiacent chamb'r s by aflexible diaphragm't (oranjequivalent piston), the diaphragmbeihgfioaded'byfa tensi'on spring '11,. -l/ I'0w'ament can betransmitted from' the" diaphragm to the levenp by-a {stem w. Thearrangement is that'when 'thevalve' o is closed, the spring fh rnoiesthe' pistonkin the direction for increasingth'e pump output. When thevalve 0 is open, the preponderating liquid pressure acting on the lfthand side "of the 'piston moves the latter'inthediiection for 'reducingthe pump output. L

Thecha'r'nber s is'n communication with the pump housing c' way fofapassageaz, andthe rotor 'c are formedsubstantially-radial passagesyenabling the'i'ot'o'r to'ser've also as a centrifugal purn'p, so thatliquid drawn from the inlet passage2 of thefuel pumpcan'bedischargedinto the housing 0 at "a pressure determined by the rateof rotation'oftherotor, the latter being driven by "any convenient partof the prime mover to be suppliedwith' l'iquid fuel.

In association with "the arrangement above described there is provideda" cylindrical chamber 3 containing aslidable throttle!"co-operatingWithanorifice'E, and the portion *of the chamber S'beneaththesaid'prifice-is connected by a pipe 6 to th above'mentioned'passage 21:.'Also at a positionabove thebrifice 5 "the 'ch'amberfl is connected bypipes "I, 8,to the servo cy'linderg at the end which is incommunicatiom'withthe pump delivery passage k. The-pipesl,Bja'r'e'interconnected through "an "isolating valve to be hereinafterdescribed.

The "throttle 4 is'arranged' at" one end of "'a rod 9 extending'from'adash-potfpiston l0 'slidable inthe chamber 3 ,"and havingth'ereina restricted orifice l I. The-pistoni-sattached'to' a tensionspring 112 which is' ad astsuepyascrew I 3.

The pipes 8, "If-and 5, thefpas'sage :v, the chamber c, andthe passagesyin the pump rotora constitute aib'y p'ass passage interconnecting thepump delivery passage '10 andthe pump inlet passage 2. The flow through'thefby-pass passageis controlled'inpartby the throttle l4 andin'p'artb'y the counter-pressure exerted by the centrifugal pump. Itfollows that the pressure in the chamber s is the sum of two variablepressures, one of them being related to the pressure in the pumpdelivery passage To and determined by the throttle 5, and the otherbeing determined by the rate of rotation of the pump rotor (1.

Assuming that the system is in a steady state,

and working at the desired rate, the valve will be open, and the passagethrough the orifice will be restricted by the throttle 4 to an extentdepending on the liquid pressures then acting on the diaphragm t andpiston 50. A change in this pressure due to either a change of pressurein the fuel delivery system, or in the counterpressure of thecentrifugal pump, will result in a corresponding change in the conditionof the valve 0. Thus, with a fall in the speed of the pump rotor, thepressure in the chamber s will fall correspondingly. The effect of thisis to cause the valve 0 to move to, or towards, its closed position andso cause the servo mechanism to vary the position of the swash plate andthereby increase the pump output. Meanwhile the said fall of pressurewill also manifest itself at the throttle, and the spring I 2 willgradually move the throttle to a more open position at a rate dependenton the dash-pot action associated with the piston I ll. Eventually a newstate of adjustment will be attained, and the liquid pressure in thechamber s will be restored to its previous amount, thus restoring theinitial condition of the system. An increase of pressure above theprevious amount in the fuel supply system will cause the throttle tomove in the direction for reducing the flow through the part 5, causingthe pump output to be reduced until the previous condition is restored.

To obviate loss of fuel from the supply system through the by-passpassage, while the prime mover is being started, there is provided theisolating valve above mentioned. In one convenient form this comprises aclosure member l4 co-operating with a seating l5 to which is connectedthe pipe 8. The closure member is carried by a diaphragm I 6 (or piston)in a hollow body part I1 which is divided by the diaphragm into twocompartments. The lower compartment is connected to the pipe 1, and theupper compartment is connected by a pipe i 8 to the pump inlet. Also theupper compartment contains a compression spring !9 which holds theclosure member on its seating until the pressure in the pum deliveryassage 70 reaches a predetermined amount. When the system is operatingnormally the closure member I4 is held off its seating by the fluidpressure acting on the diaphragm.

By this invention the desired action of the governor can be obtained ina very simple and reliable manner.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A hydraulic speed governor for a liquid operated servo mechanism forcontrolling the rate of supply of liquid fuel to a prime mover from apump driven thereby comprising, in combination, liquid pressureresponsive means arranged to actuate a valve for controlling said servomechanism, a by-pass passage afiording communication between the inletand the discharge or the pump and having a connection with said pressureresponsive means, a variable throttle for controlling liquid flow insaid by-pass passage, means for creating in said by-pass passage aliquid counter-pressure related to and varying with the speed of theprime mover and opposed to the pump discharge pressure whereby thedifference in said opposed liquid pressures actuates thepressure-responsive means, andmeans including a dash-pot responsive tothe liquid pressure in the by-pass for actuating the variable throttlein a direction to restrict flow of liquid in the by-pass when thepressure therein rises and vice versa, said throttle actuation beingeffected at a controlled rate determined by the dash-pot.

2. A hydraulic speed governor according to claim 1, comprising anisolating valve in the bypass passage for temporarily interruptingliquid flow therethrough while the prime mover is being started, andmeans operated by the pressure of liquid delivered by the pump foropening said isolating valve.

3. A hydraulic speed governor for a liquid operated servo mechanism forcontrolling the rate of supply of liquid fuel to a prime mover from apump driven thereby comprising, in combination, liquid pressureresponsive means arranged to actuate a valve for controlling said servomechanism, a by-pass passage aflording communication between the inletand outlet of the pump and having a connection with said pressureresponsive means, means forming a cylindrical chamber constituting partof said by-pass passage and having therein an orifice, a throttle valvemovable in said orifice for controlling liquid flow in the by-passpassage, a dash-pot piston connected with the throttle valve and movablein the chamber under the pressure of liquid therein to actuate thethrottle valve in a closing direction when said liquid pressure risesand vice versa, a spring acting on the piston, restricted passage meansafiording communication between parts of the chamber at opposite sidesof said piston, and means for creating in the by-pass passage a liquidcounter-pressure related to and varying with the speed of the primemover and opposed to the pump discharge pressure whereby the differencein the opposed liquid pressures in the by-pass is employed to actuatethe pressure responsive means.

4. A hydraulic speed governor according to claim 3, in which the meansfor creating the liquid counter-pressure comprise a centrifugal P p.

5. A hydraulic speed governor for a liquid operated servo mechanism forcontrolling the rate of supply of liquid fuel to a prime mover from apump driven thereby comprising, in combination, liquid pressureresponsive means arranged to actuate a valve for controlling said servomechanism, a by-pass passage afiording communication between the inletand the discharge of the pump and having a connection with said pressureresponsive means, a variable throttle for controlling liquid flow insaid by-pass passage, means for creating in said by-pass passage aliquid counter-pressure related to and varying with the speed of theprime mover and opposed to the pump discharge pressure whereby thedifierence in said opposed liquid pressures actuates the pressureresponsive means, means including a dash-pot responsive to the liquidpressure in the by-pass for actuating the variable throttle in adirection to restrict flow of liquid in the by-pass when the pressuretherein rises and vice versa, said throttle actuation being effected ata controlled rate determined by the dash-pot, and an isolating valve inthe by-pass passage for temporarily interrupting liquid flowtherethrough and comprising a chamber, a liquid pressure responsivemember dividing the chamber into two compartments one of which forms apart of the by-pass passage and is provided with a seating, a closuremember carried 5 by the liquid pressure responsive member and arrangedto co-operate with said seating, and a spring acting on the liquidpressure responsive member, the arrangement being such that pressure ofthe liquid delivered by the pump opens 10 the closure member or theisolating valve.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date Ifield et a1 July 2, 1946 Ifield July 15, 1947 Watson et a1Oct. 14, 1947 Ifield Apr. 27, 1948 Ballantyne et a1. Aug. 22, 1950Mordell et a1. Jan. 16, 1951

